Communication terminal and base station communication method using MAC control information priorities and SRB priorities

ABSTRACT

A communication terminal adjusts the transmission timing of data transmitted to a base station so that the base station can receive the data within a predetermined delay time. The communication terminal includes a reception section  701  for receiving priority of MAC control information transmitted from the base station, a priority control section  703  for defining the relationship between the priority of the MAC control information and priority assigned to DRB and SRB, and a transmission message generation section  704  for controlling so as to transmit information having a high priority early in accordance with the relationship between the priorities defined by the priority control section  703 . According to the communication terminal, a comparison is made between the priority of the MAC control information and the priority assigned to the DRB and the SRB, whereby it is made possible to control what information is to be transmitted as desired.

TECHNICAL FIELD

The present invention relates to a communication terminal and basestation for communicating in accordance with a predetermined procedure.

BACKGROUND ART

In E-UTRA/E-UTRAN standardized at present, time multiplex is adopted inboth an up link (UL) from a terminal to a base station and a down link(DL) from the base station to the terminal. In up link, when the basestation receives data from a plurality of terminals, if the receptiontimings of the data transmitted by the terminals shift, time multiplexcannot efficiently be executed. Thus, in a time multiplex system, thetransmission timings of the terminals need to be adjusted so that thebase station can receive the data transmitted by the terminals within agiven delay.

This is called uplink synchronization (also called timing adjustment,timing alignment, etc.). The operation required for each terminal toachieve uplink synchronization is a RACH procedure (Random AccessCHannel procedure). First, an outline of the RACH procedure will bedescribed and then Message 3 transmission on which the invention focusesattention will be described.

[Outline of RACH Procedure]

In E-UTRA/E-UTRAN, the RACH procedure is used in various cases.

The use reasons of the RACH procedure are specifically call connection(initial access), Handover complete, message transmission, UL/DL datatransmission and reception resuming (UL/DL data resuming), andreconnection (radio link failure recovery).

The initial access is the case where the terminal performs callconnection from an idle (RRC_IDLE) state. Since the terminal is in IDLEstate, uplink synchronization with the base station is not achieved.

The Handover complete transmission is the case where the terminalexecutes handover and the target base station is notified that theterminal moves to the target base station. The terminal has notconnected to the target base station until then and thus here achievessynchronization with the target base station.

UL/DL data resuming is the case where the terminal performingintermittent reception (DRX) starts to transmit or receive UL or DLdata. Since uplink synchronization of the terminal is got out after awhile, it is necessary to again achieve synchronization.

Radio link failure recovery is the case where after it becomesimpossible for the terminal to detect the connected cell, the terminalreconnects to a cell that is newly found (or that has been connectedbefore). The situation resembles initial access.

There are two large types of RACH procedure. One is the case where theterminal selects RACH preamble transmitted to the base station on itsown (non-dedicated RACH preamble case) and the other is the case wherethe terminal uses RACH preamble given from the base station (dedicatedRACH preamble case).

The respective operations are shown in (a) and (b) of FIG. 1. The largedifference is as follows: In the non-dedicated RACH preamble case, thereis a possibility that a plurality of terminals may use the same RACHpreamble at the same time and thus a message for checking the presenceor absence of collision (Message 4: Contention resolution) is used; inthe dedicated RACH preamble case, RACH preamble to be used is assignedby an assignment message (Message 0: RA preamble assignment).

To Message 1 and Message 2, the same applies to all cases, but inMessage 3 and Message 4, different data is transmitted in response toeach case. Only Handover complete transmission and DL data resuming canuse dedicated RACH preamble, because the base station can perform theoperation of assigning RACH preamble only in the two cases.

FIG. 2 shows the two procedures. Dedicated RACH preamble is not alwaysused for Handover complete transmission or DL data resuming andnon-dedicated RACH preamble can be used.

Another large difference between non-dedicated RACH preamble anddedicated RACH preamble is that when the base station receives dedicatedRACH preamble, it can identify the terminal. Accordingly, work forchecking which terminal sends RACH preamble in the later message becomesunnecessary.

In other words, in the non-dedicated RACH preamble case, the ID of theterminal needs to be contained in Message 3 to indicate which terminalaccesses. As the ID of the terminal, if the terminal is active(RRC_CONNECTED), C-RNTI (Controlling Radio Network Temporary Id) used incell units is used; if the terminal executes initial access, S-TMSI(S-Temporary Mobile Subscriber Id entity) used in Tracking area (unit ofmove management of IDLE terminal) or IMSI (International MobileSubscriber Identity) of the ID unique to the terminal (corresponding totelephone number) is used. In radio link failure recovery, the cellidentifier (cell ID) of the cell connected before radio link failure iscaused to occur, C-RNTI in the cell, etc., is used.

[Message 3 Transmission]

Data that can be initially transmitted to the base station by theterminal is Message 3, and information for this is assigned in Message2. However, it is known that the size of Message 3 is about 72 bits ifthe terminal is in a cell edge.

Thus, it is considered that it is difficult to transmit all informationat one time. To show how Message 3 is configured, FIGS. 3, 4, and 5 showheader configurations of MAC (Medium Access Control), RLC (Radio LinkControl), and PDCP (Packet Data Convergence Protocol) respectively. FIG.14 shows the configuration of protocol. An outline is described below:(MAC)

Three types of MAC sub-headers are provided and the minimum sub-headeris eight bits. What data is contained is indicated using LCID (LogicalChannel ID), whether or not a MAC sub-header exists following a MACsub-header is indicated in an E (Extention) field), and the data size isindicated in an L (Length) field).

MAC control element (MAC control information: as up link, C-RNTI, Bufferstatus report (BSR indicating the buffer status of the terminal), andCQI (Channel Quality Indicator indicating the channel status of theterminal) are also indicated in LCID. In this case, the size ispredetermined and thus the L field is not required.

(RLC)

A 16-bit header is defined for RLC AM (acknowledge mode) and 16 bits(10-bit SN for long data) and eight bits (five-bit SN for short data)are defined for RLC UM (unacknowledged mode).

(PDCP)

Different headers are defined in SRB (signalling radio bearer: Bearerfor carrying an RRC message of a control message) and data radio bearer(DRB, bearer for carrying data). For SRB, a 40-bit header becomesnecessary.

The data radio bearer may be called user plane radio bearer (user radiobearer).

It is considered that Handover complete contains message type(indicating the type of message), transaction id (indicating response towhich message), etc., as RRC message, and eight bits are assumed.

-   Non-patent Document 1: TS25.321: “Medium Access Control (MAC)    protocol specification”

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

From the description given above, considering transmission of Handovercomplete, it is seen that if 72 bits only are assigned to the terminalfor transmission, transmission needs to be executed twice as in Table 1.It is predetermined that BSR is transmitted after Handover is executed.In UMTS (Universal Mobile Telecommunication System), it is assumed thatMAC control information (MAC control element in LTE) always has higherpriority than SRB and DRB (refer to Non-patent Document 1).

Thus, it is assumed that the BSSR is sent earlier than Handovercomplete. In this case, transmission is executed three times as in Table2 and further transmission of Handover complete is delayed.

TABLE 1 To transmit Handover complete only 1st segment 2nd segment RRC +PDCP 24 bits 24 bits RLC 16 bits 16 bits MAC  8 bits  8 bits (LCID forRRC) (LCID for RRC) PHY (CRC) 24 bits 24 bits Total 72 bits 72 bits

TABLE 2 When BSR takes precedence over Handover complete 1st segment 2ndsegment 3rd segment RRC + PDCP  0 bits 24 bits 24 bits RLC  0 bits 16bits 16 bits MAC 48 bits  8 bits  8 bits (LBSR + LCID + (LCID for RRC)(LCID for RRC) 24 bits padding (LCID + padding bits) PHY (CRC) 24 bits24 bits 24 bits Total 72 bits 72 bits 72 bits

As described above, if MAC control element (for example, BSR) takespriority, it is through that transmission of Handover complete isdelayed. This has the following disadvantage:

(Path Switching Delay in Network)

As the base station receives Handover complete, it can reliablydetermine that the terminal moves. Thus, switching in the network (pathswitching from the former base station to a new base station) isperformed at the timing at which Handover complete is received. If pathswitching is delayed, data, etc., not transferred from the former basestation to the new base station is discarded.

FIG. 15 shows the relationship between the base station in the networkand the entity of a core network. The core network entity continues totransmit data to the previous base station (source eNB) until path isswitched to the core network entity.

There is no problem if the previous base station transfers data to a newbase station; for example, it is thought that a packet is nottransferred in real time service of VoIP, etc. To minimize this,shortening of path switching delay is demanded.

(Transmission Start Delay of Down Link)

As the base station receives Handover complete, it can reliablydetermine that the terminal moves, and can start down link datatransmission. Thus, if reception of Handover complete is delayed, whenthere is data transferred from the former base station to a new basestation, down link data transmission start is delayed.

Considering the description given above, it is undesirable that the MACcontrol element always takes precedence. Thus, the priority of the MACcontrol element needs to be controlled.

In view of the circumstances described above, it is an object of theinvention to provide a communication terminal and a base station thatcan assign priority to MAC control information and can control whatinformation is to be transmitted as desired.

Means for Solving the Problems

A communication terminal according to the present invention is acommunication terminal for communicating with a base station inaccordance with a predetermined procedure, the communication terminalcomprising: a priority control section for defining the relationshipbetween priority of MAC control information of priority assigned to MACcontrol information and priority assigned to DRB and SRB; and atransmission message generation section for controlling to transmitinformation having a high priority early in accordance with therelationship of priority defined by the priority control section.

According to the configuration described above, it is made possible tocontrol what information is to be transmitted as desired in response tothe priority of the MAC control information and the priority assigned tothe DRB and the SRB. Therefore, appropriate control responsive to thedescription and the situation of communication service is made possible.For example, when VoIP is executed, if path switching needs to beperformed rapidly, it is considered that the SRB has a higher prioritythan the BSR. Conversely, if path switching need not be performedrapidly and the buffer state of the terminal is to be understoodrapidly, the BSR can have a higher priority than the SRB.

The communication terminal of the present invention may comprise areception section for receiving the priority of the MAC controlinformation transmitted from the base station.

In the communication terminal of the present invention, the MAC controlinformation includes C-RNTI, BSR, and CQI, and the transmission messagegeneration section transmits information having a high priority early inaccordance with priorities of the DRB, the SRB, the C-RNTI, the BSR, andthe CQI.

According to the configurations described above, for example, if theC-RNTI is set to priority 1 and the BSR and the CQI is set to priority3, when the priority of the SRB is 2, only the C-RNTI can have a higherpriority than the SRB and it is made possible to control whatinformation is to be transmitted as desired.

The communication terminal of the present invention comprises a prioritytable section for holding information of the priority of the MAC controlinformation, and the reception section receives boundary informationindicating boundary of the priority of the MAC control information, andthe priority control section references the boundary information todefine the relationship between the priority of the MAC controlinformation and the priority assigned to the DRB and the SRB.

According to the configuration described above, the boundary informationof the priority of the MAC control information can be set using a smallnumber of bits, so that an increase in overhead of signaling can besuppressed.

In the communication terminal of the present invention, the prioritycontrol section specifies the priority of the MAC control information inresponse to a use reason of a RACH procedure.

According to the configuration described above, the priority of the MACcontrol information is specified in response to the use reason of theRACH procedure, whereby the transmission operation can be changed foreach RACH procedure.

In the communication terminal of the present invention, the receptionsection receives a threshold concerning the size of a message from thebase station, and the priority control section references the thresholdto define the relationship between the priority of the MAC controlinformation and the priority assigned to the DRB and the SRB.

According to the configuration described above, if the message set to betransmitted early is large, the MAC control information is transmittedearly and overhead accompanying transmission of a large message can bedecreased.

In the communication terminal of the present invention, the receptionsection receives information required for determining the priorities ofthe MAC control information and the SRB from the base station, and thepriority control section references the information to determine thepriorities of the SRB and the MAC control information.

According to the configuration described above, the priority can be setwithout a command from the network.

In the communication terminal of the present invention, the informationrequired for determining the priorities of the MAC control informationand the SRB contains information indicating whether or not service inwhich the packet loss increases because of path switching delay isreceived, information indicating whether or not handover is handoverwithin the base station, and information indicating whether or nothandover is handover between the base stations.

According to the configuration described above, the priorities of theSRB and the MAC control information can be determined without a commandfrom the network based on whether or not VoIP is used and whether or nothandover is handover in the base station or is handover between the basestations.

In the terminal of the present invention, an extension field indicatingwhether or not MAC sub-header follows is placed at the top in MACsub-header and if a resource of 72 bits only of MAC sub-header isallocated, whether or not MAC header exists is indicated by the value ofthe extension field positioned in the beginning of MAC header.

According to the configuration described above, the terminal can notifythe base station whether or not MAC header exists without using a newbit.

A base station according to the present invention is a base station forcommunicating with a communication terminal in accordance with apredetermined procedure, wherein priority is assigned to MAC controlinformation and the priority of the MAC control information istransmitted to the communication terminal.

According to the configuration described above, priority is assigned tothe MAC control information, so that it is made possible to control whatinformation the terminal transmits as desired.

In the base station of the present invention, the priority of the MACcontrol information is previously determined and only information ofboundary between MAC control information having a higher priority thanSRB and MAC control information having a lower priority than the SRB istransmitted to the communication terminal.

According to the configuration described above, the boundary of the MACcontrol information can be set using a small number of bits, so that anincrease in overhead of signaling can be suppressed.

In the base station of the present invention, the priority of the MACcontrol information responsive to a use reason of a RACH procedure istransmitted to the communication terminal.

According to the configuration described above, the priority of the MACcontrol information is specified in response to the use reason of theRACH procedure, whereby the operation of the terminal can be changed foreach RACH procedure.

In the base station of the present invention, if the size of a messageto be transmitted is greater than a predetermined size, the MAC controlinformation takes precedence.

According to the configuration described above, if the message set to betransmitted early is large, the MAC control information is transmittedearly and overhead accompanying transmission of a large message can bedecreased.

In the base station of the invention, an extension field indicatingwhether or not MAC sub-header follows is placed at the top in MACsub-header and if a resource of 72 bits only of MAC sub-header isallocated, whether or not MAC header exists is determined by the valueof the extension field positioned in the beginning of MAC header.

According to the configuration described above, the base station candetermine whether or not MAC header exists without using a new bit.

Advantageous Effects of the Invention

According to the communication terminal of the invention, a comparisonis made between the priority of the MAC control information and thepriority assigned to the DRB and the SRB, whereby it is made possible tocontrol what information is to be transmitted as desired. According tothe base station of the invention, priority is assigned to the MACcontrol information and the priority of the MAC control information istransmitted to the communication terminal, so that it is made possibleto control what information the communication terminal transmits asdesired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the operation of non-dedicated RACH preamble and dedicatedRACH preamble.

FIG. 2 shows procedures of handover complete transmission and DL dataresuming.

FIG. 3 shows the header configuration of MAC of Message 3.

FIG. 4 shows the header configuration of RLC of Message 3.

FIG. 5 shows the header configuration of PDCP of Message 3.

FIG. 6 shows the concept of Embodiment 2 of the invention.

FIG. 7 is a block diagram of a terminal according to Embodiment 2 of theinvention.

FIG. 8 shows a specific example of a procedure according to Embodiment 2of the invention.

FIG. 9 shows the concept of Embodiment 3 of the invention.

FIG. 10 is a block diagram of a terminal according to Embodiment 3 ofthe invention.

FIG. 11 describes change of priority of MAC control element for each usereason of a RACH procedure in Embodiment 3 of the invention.

FIG. 12 shows the concept of Embodiment 4 of the invention.

FIG. 13 is a block diagram of a terminal according to Embodiment 4 ofthe invention.

FIG. 14 shows the configuration of protocol of Message 3.

FIG. 15 shows the relationship between a base station in a network andthe entity of a core network.

FIG. 16 shows an outline of setting priority for each MAC controlelement in Embodiment 1 of the invention.

FIG. 17 is a block diagram of a terminal according to Embodiment 1 ofthe invention.

FIG. 18 shows an example of MAC control element priority table and anexample of boundary information in Embodiment 2 of the invention.

FIG. 19 shows operation when a base station considers the speed of aterminal in Embodiment 2 of the invention.

FIG. 20 shows operation of temporarily changing priority in Embodiment 2of the invention.

FIG. 21 shows a method of transmitting boundary information used fortransmission using semi-persistent scheduling to a terminal inEmbodiment 3 of the invention.

FIG. 22 is a block diagram of a terminal according to Embodiment 5 ofthe invention.

FIG. 23 is a flowchart to show the essence of operation according toEmbodiment 5 of the invention.

FIG. 24 shows a flow when the terminal executes initial access (callconnection), Radio link failure recovery (reconnection) in Embodiment 2of the invention.

FIG. 25 shows the configuration of a MAC sub-header used in aconventional proposition.

FIG. 26 shows the configuration of a MAC sub-header according toconventional proposition 1.

FIG. 27 shows the configuration of a MAC sub-header according toEmbodiment 6 of the invention.

FIG. 28 is a flowchart to show an outline of the operation of a terminalaccording to Embodiment 6 of the invention.

FIG. 29 shows configuration examples of MAC header according toEmbodiment 6 of the invention.

FIG. 30 shows a definition example of LCID according to Embodiment 6 ofthe invention.

FIG. 31 shows other configuration examples of MAC header according toEmbodiment 6 of the invention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   -   701, 2201 Reception section    -   702, 1101 Priority table section    -   703, 1001, 1301, 1701, 2202 Priority control section    -   704, 1002, 1302, 2203 Transmission message generation section    -   705 SRB generation section    -   706 DRB generation section    -   707 Buffer section    -   708 MAC information generation section    -   709 Transmission section

BEST MODE FOR CARRYING OUT THE INVENTION

An example wherein the priority of transmission data is defined beforeexecution of RACH procedure by a base station and a terminal will bedescribed below: Embodiments described below can be applied to thenon-dedicated RACH preamble case and the dedicated RACH preamble case ina similar manner.

Embodiment 1

SRB (signalling radio bearer: bearer for carrying an RRC message of acontrol message) and DRB (user plane radio bearer/data radio bearer:bearer for carrying data) have each a priority. As present SRB, highpriority SRB (SRB2) for sending an RRC message having a high priorityand low priority SRB (SRB1) having a priority as usual SRB exist for anRRC_CONNECTED terminal to communicate. Another SRB (SRB0) is defined forcarrying an RRC message until a terminal moves to RRC_CONNECTED ininitial access, Radio link failure recovery, etc. DRB is added inresponse to service used by the terminal; for example, DRB for VoIP, DRBfor web browsing, DRB for transferring email, and the like are set.

Priority is set for each bearer so that the base station can controlwhich bearer the terminal may transmit. Basically, SRB has a higherpriority than DB. In DRB, a bearer for service involving strictrequirement for a delay (time critical service) has a high priority.Thus, in the example, the following priority is considered:

High priority SRB>low priority SRB>DRB for VoIP>DRB for web browsing>DRBfor email

In the embodiment, priority is set for each MAC control element as likeSRB and DRB. An outline is shown in FIG. 16. As shown in the figure, forexample, if priority values are 1 to 8 and 1 is the highest, it isconsidered that C-RNTI considered to be the highest priority in the MACcontrol element is set to priority 1 and BSR, CQI, etc., considered tobe next highest priority is set to priority 3.

If the priority of high priority SRB becomes 2, only C-RNTI takesprecedence over high priority SRB. According to such operation, it ismade possible to control what information the terminal is caused totransmit as desired.

Specifically, if the terminal uses VoIP and path switching needs to bemade rapid, it is considered that the priority of high priority SRB ismade higher than that of BSR. Conversely, if path switching need not bemade rapid and the buffer state that the terminal has is to be graspedrapidly, the priority of BSR can be made higher than that of highpriority SRB.

(Block Diagram)

FIG. 17 is a block diagram of a terminal of the invention. Thecommunication terminal shown in FIG. 17 includes a reception section701, an SRB generation section 705, a DRB generation section 706, apriority control section 1701, a transmission message generation section704, a buffer section 707, a MAC information generation section 708, anda transmission section 709. The main operation and the roles of thesections are as follows:

The reception section 701 receives a message from a base station. Thereception section 701 receives the priority for each MAC control elementand sends the priority to the priority control section 1701. Thereception section 701 receives the message size transmitted by theterminal and sends the message size to the transmission messagegeneration section 704. The SRB generation section 705 creates a messageto be transmitted using SRB of an RRC message, a NAS message, etc. TheDRB generation section 706 creates user plane data.

The priority control section 1701 receives the priority for each MACcontrol element from the reception section 701. The priority controlsection 1701 defines the priority relationship between MAC controlelement and SRB such as “C-RNTI>SRB>BSR>CQI>DRB” or “C-RNTI>highpriority SRB>BSR>low priority SRB>CQI>DRB” according to the priority foreach MAC control element and the priority assigned usually to DRB andSRB. The priority control section 1701 uses the result to control thetransmission message generation section 704 so as to create atransmission message for transmitting high priority information early.

The transmission message generation section 704 creates a transmissionmessage based on the priority information from the priority controlsection 1701 and the transmission message size from the receptionsection 701. The transmission message generation section 704 receivesMAC control element from the MAC information generation section 708described later, reports transmittable bearer and the amount to thebuffer section 707, and receives information to be transmitted of SRB orDRB from the buffer section 707.

The buffer section 707 holds information from the SRB generation section705 and the DRB generation section 706 and transmits the information tothe transmission message generation section 704 in response to a commandof the transmission message generation section 704.

The MAC information generation section 708 generates MAC control elementand reports the MAC control element to the transmission messagegeneration section 704. Specifically, when C-RNTI needs to betransmitted, the MAC information generation section 708 passes C-RNTI tothe transmission message generation section 704. When BSR needs to betransmitted, the MAC information generation section 708 generates andtransmits BSR from information of the buffer section 707. Thetransmission section 709 has a role of transmitting a message created bythe transmission message generation section 704 to the base station.

As described above, according to the embodiment, the priority can be setas desired for each MAC control element, so that data to be transmittedpreferentially to the base station in Message 3 of RACH procedure can beappropriately controlled in response to the description and thesituation of communication service.

Embodiment 2

FIG. 6 shows the concept of Embodiment 2, FIG. 7 is a block diagram of aterminal, and FIG. 8 shows a specific example of a procedure of theoperation.

In Embodiment 1, the priority can be set as desired for each MAC controlelement. However, the system of Embodiment 1 involves a problem in thatthe overhead of signalling for the base station to set priority for theterminal increases. In Embodiment 2, priority in MAC control element ispreviously determined and only the boundary between the MAC controlelement having a high priority for SRB and the MAC control elementhaving a low priority is set, whereby the problem is solved. FIG. 6shows an outline.

As by (a) in FIG. 6, priority is determined in MAC control elements. Itis considered that the priority is stipulated in the specification(spec) of standardization, etc.; it may be transmitted in reportinformation, etc., or may be sent in a discrete RRC message. In theembodiment, an example wherein the priority is stipulated in thespecification (spec) of standardization, etc., will be described. Theboundary between the MAC control element having a higher priority thanSRB and the MAC control element having a lower priority than SRB is set.Specifically, any of boundaries 1 to 4 in the example by (a) in FIG. 6is specified. A signalling example at this time is shown by (b) in FIG.6. The procedure shown by (b) in FIG. 6 is executed before Message 1shown by (a) in FIG. 1.

Specifically, if boundary 2 is specified, the priority order becomes asfollows:

C-RNTI>SRB>BSR>CQI>DRB

Although one priority is under SRB, it is also considered that thepriority of the MAC control element is compared with high priority SRBfor setting as follows:

C-RNTI>high priority SRB>BSR>low priority SRB>CQI>DRB

(Block Diagram)

FIG. 7 is a block diagram of the terminal of the embodiment. Theterminal shown in FIG. 7 includes a priority control section 703 and apriority table section 702 in place of the priority control section 1701of the terminal shown in FIG. 17. Difference of the main operation andthe role of each section from those of Embodiment 1 will be described.

In Embodiment 2, a reception section 701 has a role of receivingboundary information described above and reports the boundaryinformation to the priority control section 703 in addition to the roledescribed in Embodiment 1.

The priority table section 702 has a role of holding information ofpriority in MAC control elements shown by (a) in FIG. 6 and reportingthe information to the priority control section 703.

The priority control section 703 defines the priority relationshipbetween MAC control element and SRB such as “C-RNTI>SRB>BSR>CQI>DRB” or“C-RNTI>high priority SRB>BSR>low priority SRB>CQI >DRB” according tothe boundary information from the reception section 701 and the prioritytable section information from the priority table section 702. Thepriority control section 703 uses the result to control the transmissionmessage generation section 704 so as to transmit high priorityinformation early.

(Detailed Description)

The operation of the invention will be described with FIGS. 7 and 8.FIG. 8 shows a specific example of procedure of handover transmission.

As shown in FIG. 8, first, boundary information is reported from a basestation (Source cell) to a terminal (UE) (ST8-1: RRC CONNECTIONRECONFIGURATION message). The boundary information is received by thereception section 701 and is passed to the priority control section 703.The priority control section 703 obtains information of the priority ofMAC control element from two pieces of information of the boundaryinformation received in ST8-1 and table indicating the priority in MACcontrol elements described by (a) in FIG. 6 held in the priority tablesection 702. The priority control section 703 sends the information tothe transmission message generation section 704.

Next, a response message to ST8-1 created in the transmission messagegeneration section 704 is transmitted from a transmission section 709 ofthe terminal to the base station (ST8-2: RRC CONNECTION RECONFIGURATIONCOMPLETE message).

The base station reports execution of Handover to the terminal (ST8-3:Handover Command message). The terminal executes handover in response toit. The processing is general operation and does not directly relate tothe invention and thus will not be described.

Handover Command and Handover Complete message are generic terms of aHandover command message for the terminal by the base station and amessage for the terminal to indicate completion of Handover for the basestation respectively. In E-UTRA/E-UTRAN, RRC CONNECTION RECONFIGURATIONmessage and RRC CONNECTION RECONFIGURATION COMPLETE message are used.

ST8-4: Random Access preamble and ST8-5: Random Access response executedafter ST8-3 are usual RACH procedure and will not be described indetail. After ST8-5, the transmission message generation section 704determines the message size in Message 3 based on resource allocationinformation received in ST8-5. The message size is sent from thereception section 701 to the transmission message generation section704.

If both Handover complete and BSR are to be sent and cannot be containedin one message, which takes precedence is determined depending on thepriority. That is, if BSR>SRB, BSR takes precedence over SRB and ifBSR<SRB, Handover complete takes precedence. Thus, the description sentin ST8-6, ST8-8 becomes Handover complete or BSR depending on thepriority determined by the priority control section 703.

In FIG. 18,(a) and (b) show an example of a MAC control element prioritytable and an example of boundary information respectively. Thus, the MACcontrol element priority is provided as the table and the RRC messagepriority (it may be only high priority SRB, both high priority SRB andlow priority SRB, or only low priority SRB) is reported in the boundaryinformation and thus the description to be transmitted can becontrolled.

Next, how the base station determines the boundary information will bedescribed. As described above, transmission delay of Handover Completemessage causes delay of path switching in the network. Real time servicesuch as VoIP not transferring data from the source base station to theHandover target base station as described above is largely affected bythe delay of path switching.

Thus, processing in which only a terminal executing VoIP takesprecedence in transmission of Handover Complete is considered.Effectiveness of terminal information transferred between base stationsas information for switching a path is also considered. At the time ofHandover, terminal information is transferred between the base stations.

At this time, information of the reception quality of the terminal, thebuffer state of the terminal, etc., is also transferred. If the movespeed of the terminal is not so high and the reception quality of theterminal is sufficient as information transferred between the basestations, it is considered that the priority of CQI is lowered;conversely, if the move speed of the terminal is high, it is consideredthat the priority of CQI is raised.

Service in which the buffer state easily varies and a service in whichthe buffer state hardly varies are considered. For example, in serviceof VoIP, etc., the buffer state does not so much vary. In contrast, toexecute upload, it is considered that the buffer state largely varies.

Thus, it is considered that if only service in which the buffer statehardly varies is executed, the priority of BSR is lowered and if servicein which the buffer state easily varies is executed, the priority of BSRis raised. Such operation makes it possible to control information to betransmitted by the terminal.

In the embodiment, one boundary is set for MAC control element by way ofexample, but the number of boundaries to be set can also be increased.

Specifically, it is also considered that the boundary for high prioritySRB (for example, boundary 2 by (a) in FIG. 6) and the boundary for lowpriority SRB (for example, boundary 3 by (a) in FIG. 6) are set andpriority is set such as “C-RNTI>high priority SRB>BSR>CQI>low prioritySRB>DRB.”

In the embodiment, priority of MAC control element can be set only forSRB. Alternatively, it can also be set for DRB having the highestpriority. That is, processing such as “C-RNTI>SRB>BSR>high priorityDRB>CQI>other DRB” can be realized by providing a plurality of pieces ofboundary information.

In the embodiment, the transmission example of Handover complete isshown, but it can also be applied to other cases. As a specific example,UL data resuming can be named. UL data resuming is operation in the caseof occurrence of data transmitted during DRX by the terminal.

Specifically, it is considered that the measurement result indicatingthe reception state of the terminal (Measurement report as RRC message)is transmitted and a service request for addition of a new service(service request, etc., as NAS message) is sent. The Measurement reportindicating the measurement result is required for execution of Handoverand thus is a message having a high priority.

Thus, if the move speed of the terminal is high, the message must besent early. As described above, as the base station considers the movespeed of the terminal, at the time, whether occurred data is to be sentor BSR or CQI takes precedence can be determined according to theprocessing shown in the embodiment. The operation at the time is shownin FIG. 19.

The priority of MAC control element can also be made as the order ofLCID. As described above, each MAC control element is indicated by LCID.For example, BSR is 11100, CQI is 11101, etc. The order of LCID isdefined so as to become the priority order, whereby the need forspecially providing a priority table in the terminal is eliminated.

In the embodiment, notification of Handover Command and Boundaryinformation is separate messages as shown in FIG. 8, but Boundaryinformation can be reported or changed in Handover Command.

In the embodiment, the operation of setting so as to raise the priorityof RRC message when the terminal executes VoIP and Handover completeshould take precedence, etc., is shown. However, there is a problem inthat the situation varies in Handover between cells in the same basestation.

The reason is that the need for transmitting Handover complete early iseliminated because switching of the base station does not occur. Torealize this, the operation of temporarily changing priority isconsidered.

FIG. 20 shows the operation in this case. The operation differs largelyfrom the operation in FIG. 8 in that temporary priority is assigned atST20-1 corresponding to ST8-3. The temporary priority is applied only toresponse to ST20-1: Handover Command transmitted by the base station andis applied only to Handover Complete.

In the description of the invention, attention is focused on Message 3of the RACH procedure, but the embodiment can be applied to all usualuplink transmission.

As a typical example when the embodiment is used for all usual uplinktransmission, it is considered that the terminal executes initial access(call connection), Radio link failure recovery (reconnection). A flow isshown in FIG. 24. When the terminal executes call connection orreconnection, the network does not precisely know the reception state ofthe terminal, etc. Thus, information of CQI, etc., is required.

On the other hand, however, information sent to Core network is enteredin the signal sent by the terminal at ST2406 a and if it is not sent,finally call connection does not terminate. On the other hand, ST2406 bis mainly used for acknowledgment response only.

Thus, boundary information given at ST2404 a, ST2404 b makes possiblethe operation such that SRB (namely, RRC CONNECTION SETUP COMPLETE)takes precedence at the time of initial access. Accordingly, the problemin that delay of call connection increases because of transmission ofMAC control element can be solved.

Embodiment 3

FIG. 9 shows the concept of Embodiment 3 and FIG. 10 is a block diagramof a terminal. Embodiment 2 shows the case where the same prioritysetting is used for all cases using the RACH procedure. However, sincenecessary information slightly varies for the use reason of RACHprocedure, it is considered that the priority is determined for eachreason executing the RACH procedure. Embodiment 3 makes it possible tocontrol transmission data more appropriately in response to the usereason of the RACH procedure. A priority determination example for eachreason executing the RACH procedure is shown below:

(Transmission of Handover Complete)

It is considered that if BSR is not so much changed, BSR reported fromthe source base station to the target base station can be used. Thus, itis considered that Handover complete (namely, SRB) takes precedence.

(Uplink Transmission Start Delay)

To know how much information the terminal has, BSR becomes necessary.Thus, it is considered that BSR takes precedence over SRB.

(Downlink Transmission Start Delay)

To execute downlink transmission, it is considered that CQI is required.Thus, it is considered that CQI takes precedence.

In FIG. 9,(b) shows the information indication operation to realizethis. Boundary information is thus determined for each use reason of theRACH procedure, so that it is made possible to change the operation foreach RACH procedure.

(Block Diagram)

FIG. 10 is a block diagram of the terminal of the embodiment. Theterminal shown in FIG. 10 includes a priority control section 1001 and atransmission message generation section 1002 in place of the prioritycontrol section 703 and the transmission message generation section 704of the terminal shown in FIG. 7. Only the difference will be described.The priority control section 1001 can have different priority settingfor each reason of RACH procedure and reports it to the transmissionmessage generation section 1002. The transmission message generationsection 1002 generates a transmission message using different prioritysetting for each reason of the RACH procedure.

In the embodiment, only boundary information is set for each reason ofthe RACH procedure by way of example, but the priority of MAC controlelement can also be changed for each use reason of the RACH procedure.In this case, as shown in FIG. 11, a priority table section 1101 may beincluded in place of a priority table section 702 shown in FIG. 10 andthe priority for each use reason of the RACH procedure may be set in thepriority table section 1101.

Specifically, the following examples are considered:

Handover complete: C-RNTI>BSR>CQI

UL data resuming: C-RNTI>BSR>CQI

DL data resuming: C-RNTI>CQI>BSR

The operation using different priority depending on the use reason(cause) of the RACH procedure shown in the embodiment can also beapplied to the case where different priority is set in dynamicscheduling and semi-persistent scheduling although the bearer is thesame bearer. In E-UTRA/E-UTRAN, dynamic scheduling for assigning data inPDCCH (Physical Downlink Control Channel) each time and semi-persistentscheduling for continuing to use the resource in a given period if datais once assigned in PDCCH. The semi-persistent scheduling is suited forservice in which data is sent in the same size on a regular basis suchas VoIP. However, there is a problem in that if an attempt is made totransmit information of BSR, CQI, etc., taking precedence over data ofVoIP, they cannot be entered in the resource assigned in thesemi-persistent scheduling and data of VoIP cannot be sent at a time.Then, the priority for MAC control element is also applied to DRB andfurther priority setting is changed by a scheduling method for DRB,whereby the problem can be solved. Specifically, a method oftransmitting boundary information used for transmission using thesemi-persistent scheduling to the terminal is considered (FIG. 21). Thatis, if boundary 1 is indicated, in the terminal, VoIP data takesprecedence over BSR and CQI only at the time of the semi-persistentscheduling, and BSR and CQI take precedence as usual in the dynamicscheduling.

Embodiment 4

FIG. 12 shows the concept of Embodiment 4. FIG. 13 is a block diagram ofa terminal. Embodiment 2 provides means for enabling SRB to takeprecedence over MAC control element. However, the size of a messagetaking precedence over MAC control element is large, it is consideredthat it is better to send MAC control element early.

Thus, in the embodiment, only if the message taking precedence over MACcontrol element is smaller than a predetermined size, SRB takesprecedence over MAC control element. The threshold for the message sizeis sent together with boundary information as shown by (b) in FIG. 12.

(Block Diagram)

FIG. 13 is a block diagram of a terminal of the embodiment. The terminalshown in FIG. 13 includes a priority control section 1301 and atransmission message generation section 1302 in place of the prioritycontrol section 703 and the transmission message generation section 704shown in FIG. 7. Only the difference will be described below: Thepriority control section 1301 receives and processes the threshold todetermine whether or not to transmit SRB or DRB taking precedence overMAC control element and sends the threshold to the transmission messagegeneration section 1302. The transmission message generation section1302 determines whether or not the size of SRB or DRB taking precedencefalls below the threshold and only when the size falls below thethreshold, the transmission message generation section 1302 creates atransmission message so as to transmit SRB or DRB taking precedence overMAC control element.

Embodiment 5

FIG. 22 is a block diagram of a terminal of Embodiment 5 and FIG. 23 isa flowchart to show an outline of operation. Embodiment 2 shows themethod of determining the priority of MAC control element and SRBaccording to a command from the network. Embodiment 5 shows theoperation of determining the priority without a command from a network.

(Block Diagram)

FIG. 22 is a block diagram of a terminal of the embodiment. The terminalshown in FIG. 22 includes a reception section 2201, a priority controlsection 2202, and a transmission message generation section 2203 inplace of the reception section 701, the priority control section 703,and the transmission message generation section 704.

Unlike the reception section 701, the reception section 2201 does notreceive boundary information and does not report it to the prioritycontrol section 703, but sends information necessary for determining thepriority of MAC control element and SRB to the priority control section2202. The information necessary for determining the priority of MACcontrol element and SRB is information as to whether or not service inwhich packet loss increases because of path switching delay such as VoIPis received, whether Handover is Handover in a base station or Handoverbetween base stations, etc.

Unlike the priority control section 703, the priority control section2202 determines the priority of SRB and MAC control element based oninformation received from the reception section 2201. The priority isdetermined when the transmission message generation section 2203 createsa transmission message.

The transmission message generation section 2203 reports the contents ofa message scheduled to be transmitted to the priority control section2202. The transmission message generation section 2203 checks thepriority in the priority control section 2202 each time it creates atransmission message.

(Flowchart)

FIG. 23 shows the operation of determining the priority of SRB and MACcontrol element based on whether or not VoIP is used and whether or notHandover is Handover between base stations when Handover complete istransmitted.

At ST2301, transmission of Handover complete from the transmissionmessage generation section 2203 of the terminal to the base station isstarted. The transmission message generation section 2203 checks thepriority in the priority control section 2202.

The priority control section 2202 determines whether or not VoIP is usedat ST2302. If VoIP is not used, the priority control section 2202 goesto ST2304; if VoIP is used, the priority control section 2202 goes toST2303. At ST2303, the priority control section 2202 determines whetherthe Handover is Handover between base stations or Handover within basestation. If the Handover is Handover within base station at ST2303, thepriority control section 2202 goes to ST2304; if the Handover isHandover between base stations, the priority control section 2202 goesto ST2305.

At ST2304, the priority control section 2202 determines that MAC Controlelement takes precedence as path switching delay caused by HandoverComplete delay does not introduce a problem. Conversely, at ST2305, thepriority control section 2202 determines that Handover complete takesprecedence because Handover Complete delay introduces a problem. Theresult is reported to the transmission message generation section 2203,which then generates a transmission message based on the result.

In the embodiment, the terminal determines the priority for MAC controlelement of SRB based on whether or not VoIP is executed and whether ornot Handover is Handover between base stations, but any other conditionmay be used. Specifically, it is also considered that if the move speedof the terminal is high, CQI takes precedence and if the move speed islow, CQI does not take precedence. It is also considered that ifvariation of the buffer state in the terminal is fierce, BSR takesprecedence and variation is not fierce, BSR does not take precedence.

In the embodiment, whether or not VoIP is executed is adopted as onecriterion of determination, but determination may be made simply basedon whether or not service not transferred between base stations exists.DRB using UM of RLC is not transferred. Thus, whether or not DRB usingUM of RLC exists can be used as a determination criterion.

Further, whether or not DRB using RLC UM is equal to or greater than onepriority can be used as a determination criterion. Accordingly,determination of the priority of SRB affected by DRB of RLC UM having alow priority can be circumvented.

Embodiment 6

FIG. 27 shows the configuration of a MAC sub-header of Embodiment 6 andFIG. 28 is a flowchart to show an outline of the operation of aterminal. The embodiment shows how a base station distinguishes thedescription when a terminal selects RACH preamble transmitted to thebase station on its own (non-dedicated RACH preamble case).

When a terminal selects RACH preamble transmitted to the base station onits own, the base station does not understand whether the terminal wantsto execute initial access, wants to transmit Handover complete, or elseif it receives only RACH preamble (Message 1 shown by (a) in FIG. 1).Thus, the base station knows what the description of Message 3 shown by(a) in FIG. 1 is at the point in time receiving Message 3. At this time,one problem exists. It is caused by the fact that whether or not headerof MAC is used in Message 3 varies depending on a condition.Specifically, if a resource for only sending 72-bit information to theterminal is allocated, header of MAC is not contained and directly RRCmessage is contained in the case of call connection, or reconnection;header of MAC is contained in Handover complete transmission, UL/DL datatransmission-reception resuming. If a resource for sending 144-bitinformation, for example, larger than 72 bits is allocated, MAC headeris contained even in the case of call connection, reconnection. Thus,the base station needs to determine whether or not MAC header iscontained if 72 bits only are allocated to the terminal.

To solve this, non-patent document (R2-080162: Message 3 encoding) makestwo propositions.

(Conventional Proposition 1)

The first proposition uses the configuration of the present MACsub-header (see (a) in FIG. 25) described in non-patent document(TS36.321 V8.0.0: “Evolved Universal Terrestrial Radio Access (E-UTRA);Medium Access Control (MAC) protocol specification”) and uses an LCID(Logical Channel IDentifier) field (LCID field) at the top. The LCIDfield is a location to enter LCID corresponding to carried data or LCIDcorresponding to MAC control element and according to this, thereception party can identify what the received data is.

As a specific method described in the document, the first two bits offive-bit LCID are used to indicate whether or not MAC header exists; forexample, if the value of the first two bits is “11,” it is assumed thatMAC header exists and if the value is “00,” “01,” or “10” other than“11,” it is assumed that MAC header does not exist. In the case of RRCmessage in call connection, reconnection, namely, RRC CONNECTIONREQUEST, RRC CONNECTION RE-ESTABLISHMENT REQUEST, it is considered thatthe first two bits are used as Message type indicating RRC message.Thus, if the value is “00,” “01,” or “10,” the message received in RRCis identified as RRC CONNECTION REQUEST, RRC CONNECTION RE-ESTABLISHMENTREQUEST. For example, if the value is “00,” the message is RRCCONNECTION REQUEST and if the value is “01,” the message is RRCCONNECTION RE-ESTABLISHMENT REQUEST.

As the disadvantage in this case, the area that can be indicated in LCIDis limited. If the terminal selects RACH preamble transmitted to thebase station on its own, it needs to report C-RNTI the base station andthe information must be contained. Thus, it becomes necessary to reserveeight LCIDs of 32 for MAC control element containing C-RNTI. In fact,however, it is considered that eight MAC control elements containingC-RNTI are not defined, and thus LCIDs are reserved fruitlessly.

Here, other fields in the MAC sub-header will be described. An extensionfield (E) indicates whether or not MAC sub-header further continues. Ifthe value is “0,” it indicates that data or MAC control element isentered; if the value is “1,” it indicates that MAC sub-headercontinues. FIG. 26 shows a configuration example wherein a plurality ofMAC sub-headers continue. In FIG. 26,(a) shows an example wherein only aMAC sub-header without a length field (L field) shown in FIG. 25 formsMAC header. The length field indicates the size of data to be sent andenables the reception party to know where the next data or MAC controlelement begins. The MAC control element has a fixed length and thelength field is not required and the last data is not followed by anydata and thus the length field need not be entered. There are the twotypes of length fields: 7-bit length field ((b) in FIG. 26) and 15-bitlength field ((c) in FIG. 26). A format field (F field) indicates whichof the two types is used. A reserved bit (R bit) is defined for laterextension.

(Conventional Proposition 2)

The second proposition uses another MAC header configuration (see (b) inFIG. 25). The first reserved bit is used to indicate whether or not MACheader exists. That is, if the value is “0,” MAC header exists and ifthe value is “1,” MAC header does not exist. In RRC, the first bit isalways set to “1” and thus only “10” and “11” can be used foridentifying the Message type. If the value is “10,” the Message type isRRC CONNECTION REQUEST and if the value is “11,” the Message type is RRCCONNECTION RE-ESTABLISHMENT REQUEST.

The problem in this case exists in that all Message types are used andthus new RRC message cannot be defined. Thus, it is desirable that therange that can be defined as LCID is not used fruitlessly and an areathat can be used for Message type is ensured so that a new RRC messagecan be defined.

This Embodiment

As shown in FIG. 27, the configuration of the MAC header in theembodiment is characterized in that the extension field exists at thetop and whether or not MAC header exists can be determined by the valueof the extension field. The feature that if only 72 bits are allocatedfor transmission, the necessity for using a plurality of MAC sub-headersis small is utilized and if MAC header exists, the extension field isalways set to “0” and only one MAC sub-header is used. Therefore, if theextension field is set to “0,” the reception party performs processingas MAC header exists and if the extension field is set to “1,” thereception party assumes that MAC header does not exist and performsprocessing in RRC as RRC message. In RRC, the first two bits are used toidentify the message. As a specific example, if the value of the firsttwo bits “10,” the message is RRC CONNECTION REQUEST and if the value is“11,” the message is RRC CONNECTION RE-ESTABLISHMENT REQUEST.

In the system, the bit is the second bit of the MAC header, but not usedas MAC and is a reserved bit. Thus, for extension in MAC in the future,the reserved bit can be used. Conversely, if an RRC message needs to beadded, the bit can be used. Specifically, whether or not MAC headerexists is not checked using the extension field only and when theextension field and the reserved bit corresponding to the first two bitsof the MAC header are checked, if the value is “00,” it is determinedthat no MAC header exists. Accordingly, the three values of “01,” “10,”and “11” can be used to indicate the RRC message. Thus, in the system,the extension field is used to identify the presence or absence of MACheader, whereby extension of MAC or addition of RRC message is madepossible.

The operation of the terminal according to the embodiment will bedescribed below with FIG. 28:

At ST2801, the terminal checks the size allocated in Random AccessResponse. If the allocated size is larger than 72 bits, the process goesto ST2803. If 72 bits are allocated, the process goes to ST2804. AtST2804, the terminal determines whether call connection or reconnectionis executed. That is, the terminal determines whether or not MAC headeris used. To use MAC header, the process goes to ST2805; not to use MACheader, the process goes to ST2806. When the process goes to ST2805, ifthe terminal selects RACH preamble on its own (namely, Non-dedicatedRACH preamble), the process goes to ST2806; if RACH preamble given fromthe base station is used, the process goes to ST2803.

At ST2803, the terminal uses MAC header as usual and createstransmission data. On the other hand, at ST2806, the terminal createstransmission data so that the first extension field of MAC header is setto “0.” In FIG. 29,(c), (d), (e), and (f) show MAC header configurationexamples at this time. FIG. 30 shows a definition example of LCID.

In FIG. 29,(c) shows the case where only C-RNTI is transmitted. Here, 16bits of 40 bits are used as C-RNTI and the remaining 24 bits arepadding. Thus, LCID (11000 in FIG. 30) indicating that C-RNTI andpadding are entered is entered.

In FIG. 29( d), C-RNTI and BSR are transmitted and LCID (11001 in FIG.30) indicating that C-RNTI and BSR are entered is entered. This is usedwhen BSR takes precedence over handover complete.

In FIG. 29( e), C-RNTI and DCCH (Dedicated Control Channel) istransmitted. Here, DCCH is a name as Logical channel of SRB describedabove and is separated into a plurality of DCCHs as SRB is separatedinto high priority SRB and low priority SRB. LCID can be defined as itindicates only that C-RNTI and high priority SRB are transmitted later;conversely, LCID can be defined as it indicates only that C-RNTI and lowpriority SRB are transmitted later, or both may be defined. FIG. 30shows an example wherein both are defined. LCID responsive to actuallytransmitted DCCH is set (11010 or 11011 in FIG. 30).

In FIG. 29( f), C-RNTI and CQI are transmitted. Thus, LCID (11100 inFIG. 30) indicating that C-RNTI and CQI are entered is entered.

At ST2807, the terminal transmits a message with no MAC header. Examplesof transmission data at the time are shown by (a) and (b) in FIG. 29 asthe call connection time and reconnection time. Locations of informationother than Message type may be different locations.

According to the operation of the embodiment, the range that can bedefined as LCID is not used fruitlessly and it is made possible toensure an area that can be used for Message type so that a new RRCmessage can be defined.

In the description given above, LCID is defined so as to combine C-RNTIand any other information by way of example, but any other method isalso possible. If the terminal selects RACH preamble on its own, thebase station can predict that the terminal enters C-RNTI in Message 3.Thus, if operation is predetermined so as to enter C-RNTI following MACheader whenever the terminal selects RACH preamble on its own, the needfor defining LCID so as to combine C-RNTI and any other information iseliminated. Specifically, FIG. 31 shows examples. In FIG. 31( a) showsthe case where only C-RNTI is entered and the remainder is padding. Inthis case, the terminal enters LCID indicating padding as LCID. If theterminal selects RACH preamble on its own, the base station understandthat C-RNTI is always entered following MAC header and it is madepossible for the base station to understand that RNTI comes followingMAC header, followed by padding. Other cases are shown by (b), (c), and(d) in FIG. 31; the operation is similar and it is made possible for thebase station to understand that C-RNTI exists and is followed byinformation indicated in LCID.

C-RNTI is entered just after MAC header by way of example, but can alsobe set in any other location.

This application is based on Japanese Patent Application No. 2008-023171filed on Feb. 1, 2008, the contents of which are incorporated herein byreference.

While various embodiments of the invention have been described, it is tobe understood that the invention is not limited to the items shown inthe embodiments described above and the invention is also intended forthose skilled in the art to make modifications and application based onthe Description of the invention and well-known arts and themodifications and the application are contained in the scope to seekprotection.

INDUSTRIAL APPLICABILITY

The invention can be used as a communication terminal, a base station,etc., that can assign priority to MAC control information and cancontrol what information is to be transmitted as desired.

1. A communication terminal for communicating with a base station inaccordance with a defined procedure, the communication terminalcomprising: a priority control section configured to define arelationship between MAC (Medium Access Control) priorities, which arerespectively assigned to a plurality of MAC control informationelements, and radio bearer (RB) priorities respectively assigned to aDRB (Data Radio Bearer) and each of a plurality of SRBs (SignallingRadio Bearers), wherein the plurality of SRBs convey RRC (Radio ResourceControl) messages or NAS (Non-Access Stratum) messages, the prioritycontrol section being further configured to compare the MAC prioritieswith the RB priorities of the SRBs; and a transmission messagegeneration section configured to control transmission of information soas to transmit information on an SRB having a higher RB priority earlierthan a MAC control information element having a lower MAC priority inaccordance with the relationship between the MAC and RB prioritiesdefined by the priority control section.
 2. The communication terminalaccording to claim 1, further comprising a reception section configuredto receive from the base station a configuration information elementthat defines the RB priorities, whereas the MAC priorities are fixed. 3.The communication terminal according to claim 1, wherein: the MACcontrol information elements include a Terminal Identifier, a BufferStatus Report, and a Channel Status Information, wherein the MAC controlinformation elements have MAC priorities in decreasing order from theTerminal Identifier, the Buffer Status Report, and the Channel StatusInformation, and the transmission message generation section transmitsinformation on the DRB or SRB having a higher RB priority, or a MACcontrol information element having a higher MAC priority, earlier inaccordance with the RB priorities of the DRB; and the SRBs; and the MACpriorities of the Terminal Identifier, the Buffer Status Report, and theChannel Status Information.
 4. The communication terminal according toclaim 1, further comprising a priority table section configured to storeinformation regarding the MAC priorities, wherein: the reception sectionreceives boundary information indicating a boundary of the MACpriorities, and the priority control section references the boundaryinformation to define the relationship between the MAC priorities andthe RB priorities respectively assigned to the DRB and the plurality ofSRBs.
 5. The communication terminal according to claim 1, wherein: thepriority control section specifies the MAC priorities in response to ause reason for a RACH procedure.
 6. The communication terminal accordingto claim 1, wherein: the reception section receives information, whichis required for determining the MAC priorities and the RB priorities ofthe SRBs, from the base station, and the priority control sectionreferences the received information to determine the RB priorities ofthe SRBs and the MAC priorities.
 7. The communication terminal accordingto claim 6, wherein: the information required for determining the MACpriorities and the RB priorities of the SRBs contains informationindicating whether or not a service is received in which a packet lossincreases due to a path switching delay, information indicating whetheror not a handover is a handover within the base station, and informationindicating whether or not a handover is a handover between basestations.